U.S. Pat. No. 5,407,498 dated Apr. 18, 1995 is directed to an apparatus having a retort mounted for rotation about a horizontal axis and containing a particulate material therein which is fluidized while the retort is rotated. The retort is mounted in a cantilevered relation from an axle secured to one end of the generally cylindrical retort. Gas conduits extend through the end axle and gas may enter the retort and be exhausted from the retort through the gas conduit. Filters on the ends of the conduits prevent the flow of solid particles or particulate material into or out of the retort. Thus, particulate material cannot be loaded into the retort or unloaded from the retort while the retort is being rotated. Further, even when the retort is not being rotated, an end cap is required to be removed in order to provide access to a port for loading or unloading the particulate material. Also, the filters shown on the inner ends of the gas conduits within the retort are easily clogged with particulate material embedded within the filters.
It is desirable to have a retort which may be easily loaded with particulate material and unloaded in a minimum of time and without any loss of the particulate material by leakage or the like. It is particularly desirable to have such a loading and unloading means which may be utilized during operation of the retort while the retort is rotated.
As set forth in U.S. Pat. No. 5,407,498 metallurgical operations rely on the movement of certain elements within the solid matrix of the metal to be treated. Metallurgical operations rely on chemical reaction between elements which may be physically brought together or may be induced to come together by diffusion. An element is any chemical element or substance listed in the periodic table. Elements move within the solid metal by a process of diffusion. Diffusion is encouraged when an element is attracted to another element with which it is more reactive within the same contiguous metal structure. Diffusion also occurs when metals tend to form a more homogenous solid solution. Diffusion of an element from one metal to another or between a gaseous atmosphere and a metal also takes place when the materials are in intimate contact. The employment of precise pressures is often desirable to assist in this transfer.
As an example, fine metal particles or powders of nickel and aluminum can be intermixed and brought to a temperature well below the melting point of either metal and they will react to form a nickel aluminide intermetallic compound. The combining of nickel and aluminum powders produces substantial amounts of heat. This heat can raise the temperature of operation, which further speeds the combination and eventually an uncontrolled or runaway operation can happen. Temperatures can be produced which are sufficient to melt the powders so that they agglomerate together in an undesirable mass.
Water atomized iron particles or powders which contain excess carbon and oxygen can be reduced by a combination of diffusion within the powder and chemical reactions at the surface. The oxygen is generally an oxide on the surface of the powder but the carbon is diffused throughout. By bringing the powders into intimate contact in the pressure of hydrogen, a reaction is generated at the surface whereby carbon and oxygen combine to form a carbon oxygen gaseous compound and hydrogen and oxygen combine to form gaseous water. Carbon within the powder migrates by diffusion to the surface and reacts with the oxygen. Heat must be added to initiate the reactions and good thermal transfer helps maintain constant temperatures which are important for a controlled reaction. In some cases, the reaction changes from endothermic to exothermic as the carbon is dissipated and hydrogen begins to combine directly with the remaining oxygen.
Ideally, the elements in the fluidizing process to undergo a reaction will be brought into intimate contact with each other and will be held in contact for sufficient time for the chemical reaction to take place. Further, it is important that if heat is to be added during the reaction, it must be added with great uniformity so that the reaction takes place at the desired temperature. In the case of those reactions which generate heat it is even more important to have good thermal transfer so the heat can be removed from the operation to avoid an undesired rise in temperature.
The process or method as shown in U.S. Pat. No. 5,407,498 is not concerned with maintaining the exothermic or endothermic reactions of the particulate material at a precise uniform temperature during fluidizing within a rotating retort by (1) precisely controlling the addition of heat to the retort or the release of heat from the retort to match the heat loss or gain to or from the retort resulting from chemical reactions within the retort, and (2) precisely adding or injecting another material into the rotatable retort during fluidizing of the initial particulate material in the retort so that heat generated or lost matches the heat induced to or exiting from the retort as a result of said injection of particulate material.